1. Field of the Invention
The present invention relates to an ink jet recording method, and more particularly, to an ink jet recording method that reduces nozzle clogging, is excellent in discharge stability, and is excellent in ink absorptivity, print density, bleeding resistance over time, light fastness and the like.
2. Description of the Related Art
Recently, with rapid development of the information technological industry, various information processing systems have been developed, and recording methods and recording apparatuses suitable for the information processing systems have also been developed, and respectively put into practical use. Of these recording methods, ink jet recording methods are widely used for both home and office use due to the fact that recording can be performed on various recording materials, and that the hardware (apparatus) thereof is relatively inexpensive and compact and has quiet operation.
In addition, with the increase in resolution of recent ink jet printers, it has also become possible to obtain a so-called photographic level high image quality recorded product, and with such advances in hardware (apparatus), recording media for ink jet recording have also been variously developed.
Desirable properties for recording media for ink jet recording generally include: (1) a quick drying property (high absorption speed of ink), (2) appropriate and uniform diameters of ink dots (no occurence of bleeding), (3) excellent granularity, (4) high circularity of dots, (5) high color density, (6) high saturation (no occurence of dullness), (7) excellent water resistance, light fastness and ozone resistance of printed portion, (8) high whiteness of recording media, (9) excellent storability of recording media (no yellowing even in storage for long period of time, no occurence of color bleeding of images in storage for a long period of time (excellent color-edge definition over a long period of time)), (10) no tendency of deform and excellent dimensional stability (a sufficiently small amount of curling), (11) excellent running property in hardware.
In the application of photographic glossy paper used for the purpose of obtaining a so-called photographic level high image quality recorded product, glossiness, surface smoothness, photographic paper-like feeling similar to that of silver salt photographs and the like are also required, in addition to the various properties mentioned above.
In order to satisfy such requirements, a wide variety of types of recording media have been conventionally proposed. For example, in order to obtain excellent absorptivity, color forming property, resolution and the like, Japanese Patent Application Laid-Open (JP-A) No. 2-276670 proposes a recording medium having a porous layer containing inorganic particles (alumina hydrate or the like) on a substrate. JP-A No. 4-101880 proposes a recording medium having an ink fixation layer constituted of a transparent resin which is dissolved or swollen by a solvent in the ink, on a substrate. Further, Japanese Patent Application Publication (JP-B) No. 2-18146 and JP-B No. 2-31673 propose recording media having thermoplastic resin particles, an emulsion and latex on a substrate.
Japanese Patent Application Laid-Open (JP-A) No. 9-99634 proposes a recording medium containing a polymer complex obtained by mixing a binder and organic particles once they have been dissolved, whose receiving layer contains a polymer complex composed of a basic polymer and a styrene/(meth) acrylic acid polymer. JP-A No. 9-156211 proposes a recording medium having a transparent support carrying thereon an ink receiving layer made of a water-soluble resin and cross-linked polymer fine particles having an average particle size of 200 nm or less, and having a sheet permeability of 80% or more. JP-A 10-324053 proposes a recording medium having a porous coating layer formed of a coating auxiliary and an emulsion containing nitrates of carboxycellulose.
However, while such conventional technologies improve various abilities of the recording media such as ink absorptivity, resolution, image density, transparency, and glossiness of images formed of the recording media, even in the case of these recording media, several problems occur when high quality images comparable to silver salt photographs are printed at high speed, due to remarkable progress of recent recording apparatus (hardware).
For example, a recording medium having a porous layer composed of inorganic particles (alumina hydrate or the like) formed on the surface of the medium, disclosed in JP-A No. 2-276670, has excellent image quality and glossiness. However, its surface is easily scratched, whereby, the medium tends to be scratched during conveyance depending on the conveying method in a printer. Further, because of a combination of inorganic particles and an organic resin, when the combination is applied to a transparency type sheet such as an OHP film or the like, even if the transparency is high and the haze value is relatively low, there is a problem in that the shadow of the sheet is projected.
In the case of a recording medium having an ink fixation layer using a resin which is dissolved or swollen in a solvent for an ink such as described in JP-A No. 4-101880, there is a problem in that in ink drying speed is slow, and the medium remains sticky for a while after recording. Further, there is also a problem in that sufficient water resistance of the ink receiving layer itself cannot be obtained, and migration of a dye occurs under the influence of humidity. Furthermore, due to lack of water resistance of ink receiving layer itself, there is also a problem in that when recording is carried out using a pigment as a colorant, cracks form at printed parts (particularly, at solid portions).
In the case of a recording medium having an ink receiving layer composed of thermoplastic resin particles, emulsion and latex formed on a substrate such as recording media described in Japanese Patent Application Publication (JP-B) Nos. 2-18146 and 2-31673, there is a problem in that since the medium utilizes only the gaps between thermoplastic resin particles, although the ink absorption speed is high, it is necessary to increase the thickness of an ink receiving layer to obtain sufficient ink absorbing ability, resulting in a decrease in the transparency and strength of the layer.
In the case of a recording medium having an ink receiving layer composed of a combination of a binder and organic particles as provided in JP-A No. 9-99634, a binder and organic particles are first dissolved in a solvent and then mixed to obtain a polymer complex which is used to form an ink receiving layer. Under this constitution, sufficient cavities are not formed in the ink receiving layer, and sufficient ink absorption speed cannot be expected.
In the case of a recording medium having an ink receiving layer composed of a water-soluble resin and cross-linked polymer fine particles having an average particle size of 200 nm or less formed on a transparent support, as described in JP-A No. 9-156211, since a water-soluble resin is used as a binder, sufficient gaps cannot be formed among the fine particles. Additionally, since a water-soluble resin is mixed in a high ratio of 1:1 to 1:10 based on the fine particles, it is difficult to increase ink absorption speed in the gaps.
In the case of a recording medium having a porous coating layer formed of a coating auxiliary and an emulsion containing nitrates of carboxy cellulose as described in JP-A No. 10-324053, gaps are formed among the emulsion particles. However, it is difficult to control a pH value in the porous coating layer, and when the pH value is low in the acidic range, a dye undergoes specific aggregation after printing with the ink, sometimes resulting in a color tone different from that of a conventional dye.
Known ink compositions for ink jet recording include oil-based inks, aqueous inks, and solid inks. Aqueous inks are preferable from the viewpoints of production suitability, handling property, odor, and safety. However, most aqueous inks exhibit a lack of water resistance since the dye is water-soluble and cause bleed in printing on normal paper to deteriorate printing quality, and these inks also have poor light fastness. Further, “photographic level image quality paper” having an ink receiving layer containing porous inorganic fine particles provided on the surface of the paper has a drawback in that image storability is poor due to the influence of an oxidizing gas.
Aqueous inks using a pigment or a disperse dye for the purpose of solving aforementioned these problems are proposed, for example, in JP-A Nos. 56-157468, 4-18468, 10-110126 and 10-195355. However, in the case of these aqueous inks, there are problems in that water resistance is not sufficient (although it is improved to a certain extent), the storage stability of a dispersion of the pigment or the disperse dye in the aqueous ink is low, and clogging at ink discharge ports tends to occur. Further, the photographic level image quality paper also has a problem in that the ink using the pigment or the dye shows poor permeability into the paper, and the pigment and the dye are easily peeled from the surface when rubbed with fingers.
For example, JP-A Nos. 58-45272, 6-340835, 7-268254, 7-268257 and 7-268260 provide a method of enclosing a dye in urethane or polyester dispersion particles. However, in the case of an ink jet ink obtained by this method, the color tone is insufficient, color reproducibility is not sufficient, and color fading resistance is also insufficient. In the case of printing on photographic level image quality paper, abrasion resistance to a rubber eraser and the like is not satisfactory.
As described above, an ink jet recording method which exhibits an excellent handling property, odorlessness and safety, and at the same time, has a small dispersed particle size and has excellent storage stability and stability of a dispersion over time, and which therefore, when applied to an ink composition, provides excellent ink ejecting stability with no clogging at the nozzle, shows no paper-dependency, and is excellent in color forming property and color tone (hue), and which, even when the photographic level image quality paper is used, shows excellent ink permeability, provides excellent water resistance and light fastness after printing, and particularly excellent image storability and abrasion resistance, and enables recording of high image quality at high density, has not yet been provided to date.